+ sprintf(path, "/dev/tty%u", s->vtnr);
+ s->vtfd = open(path, O_RDWR | O_CLOEXEC | O_NONBLOCK | O_NOCTTY);
+ if (s->vtfd < 0)
+ return log_error_errno(errno, "cannot open VT %s of session %s: %m", path, s->id);
+
+ return s->vtfd;
+}
+
+int session_prepare_vt(Session *s) {
+ int vt, r;
+ struct vt_mode mode = { 0 };
+
+ if (s->vtnr < 1)
+ return 0;
+
+ vt = session_open_vt(s);
+ if (vt < 0)
+ return vt;
+
+ r = fchown(vt, s->user->uid, -1);
+ if (r < 0) {
+ r = -errno;
+ log_error_errno(errno, "Cannot change owner of /dev/tty%u: %m", s->vtnr);
+ goto error;
+ }
+
+ r = ioctl(vt, KDSKBMODE, K_OFF);
+ if (r < 0) {
+ r = -errno;
+ log_error_errno(errno, "Cannot set K_OFF on /dev/tty%u: %m", s->vtnr);
+ goto error;
+ }
+
+ r = ioctl(vt, KDSETMODE, KD_GRAPHICS);
+ if (r < 0) {
+ r = -errno;
+ log_error_errno(errno, "Cannot set KD_GRAPHICS on /dev/tty%u: %m", s->vtnr);
+ goto error;
+ }
+
+ /* Oh, thanks to the VT layer, VT_AUTO does not work with KD_GRAPHICS.
+ * So we need a dummy handler here which just acknowledges *all* VT
+ * switch requests. */
+ mode.mode = VT_PROCESS;
+ mode.relsig = SIGRTMIN;
+ mode.acqsig = SIGRTMIN + 1;
+ r = ioctl(vt, VT_SETMODE, &mode);
+ if (r < 0) {
+ r = -errno;
+ log_error_errno(errno, "Cannot set VT_PROCESS on /dev/tty%u: %m", s->vtnr);
+ goto error;
+ }
+
+ return 0;
+
+error:
+ session_restore_vt(s);
+ return r;
+}
+
+void session_restore_vt(Session *s) {
+ _cleanup_free_ char *utf8 = NULL;
+ int vt, kb = K_XLATE;
+ struct vt_mode mode = { 0 };
+
+ vt = session_open_vt(s);
+ if (vt < 0)
+ return;
+
+ (void) ioctl(vt, KDSETMODE, KD_TEXT);
+
+ if (read_one_line_file("/sys/module/vt/parameters/default_utf8", &utf8) >= 0 && *utf8 == '1')
+ kb = K_UNICODE;
+
+ (void) ioctl(vt, KDSKBMODE, kb);
+
+ mode.mode = VT_AUTO;
+ (void) ioctl(vt, VT_SETMODE, &mode);
+
+ fchown(vt, 0, -1);
+
+ s->vtfd = safe_close(s->vtfd);
+}
+
+void session_leave_vt(Session *s) {
+ int r;
+
+ assert(s);
+
+ /* This is called whenever we get a VT-switch signal from the kernel.
+ * We acknowledge all of them unconditionally. Note that session are
+ * free to overwrite those handlers and we only register them for
+ * sessions with controllers. Legacy sessions are not affected.
+ * However, if we switch from a non-legacy to a legacy session, we must
+ * make sure to pause all device before acknowledging the switch. We
+ * process the real switch only after we are notified via sysfs, so the
+ * legacy session might have already started using the devices. If we
+ * don't pause the devices before the switch, we might confuse the
+ * session we switch to. */
+
+ if (s->vtfd < 0)
+ return;
+
+ session_device_pause_all(s);
+ r = ioctl(s->vtfd, VT_RELDISP, 1);
+ if (r < 0)
+ log_debug_errno(errno, "Cannot release VT of session %s: %m", s->id);